1. Field of the Invention
The present invention relates to a fuel cell system and a control method thereof.
2. Related Art
In recent years, fuel cell systems have received attention as a new source of power for automobiles. Fuel cell systems are provided with a fuel cell stack that generates power by allowing reactant gases (hydrogen and air) to undergo a chemical reaction, and reactant gas supply devices that supply reactant gases to the fuel cell via reactant gas channels, for example. The fuel cell stack is a stack structure in which from several tens to several hundreds of fuel cells are layered. In this regard, each fuel cell is configured by sandwiching a membrane electrode assembly (MEA) with a pair of separators, and the membrane electrode assembly is configured by the two electrodes of an anode and a cathode, and a solid polymer electrolyte membrane sandwiched by these electrodes.
In order to suppress the consumption amount of reactant gases as much as possible in a fuel cell vehicle with such a fuel cell system as the source of power, it is preferable to stop the supply of reactant gases to the fuel cell stack in a case of power generation being continually performed in an idle operation state such as while waiting at a traffic light, for example. Patent Document 1 proposes a technology to consume the hydrogen and oxygen staying in the fuel cell stack and system to prevent the fuel cell stack from being left as is in a high-voltage state, thereby suppressing degradation of the fuel cell stack, by continually producing generated electric current from the fuel cell stack, i.e. by continuing discharge of the fuel cell stack, even after stopping the supply of such reactant gases.    Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2006-294304